Process of saltpeter manufacture



Patented Celt. 2d, v i922.

THOMAS C. MEADOWS, OF NEW YORK, IVIA'IHIAS HAUBER, JR., OF HAVERSTRAW, NEW

I YORK, AND HARRY WILLIAMS CHARLTON, OF NEW YORK, N. Y.

PROCESS 01E SALTIPETER MANUFACTURE.

No Drawing.

To all whom it may concern:

Be it known that we, THOMAS C. MEADOWS, MATHIAS HAUBER, Jr., both citizens of the United States, and HARRY W11.- LIAMS CHARLTON, a citizen of Canada, said Mnnnows and the said CHARLTON each residing at New York city, county of New York, and State of New York, and the sad HAUBER residing at Haverstraw, county of Rockland, State of New York, have invented certain new and useful llmprovements in Processes of Saltpeter Manufacture; and we do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to the recovering of potassium from greensand and has for its object the production of a process which will be simpler and more efficient than those heretofore proposed.

With these and other objects in view the invention consists in the novel steps and combination of steps constituting the process, all as will be more fully hereinafter disclosed and particularly pointed out in the claims.

As an example of this process we digest 85 parts of greensand, 85 parts of lime, 10.15 parts sodium nitrate, 1 1.3 parts sodium hydroxide, 36.15 parts potassium nitrate, and 425 parts of water at a steam pressure corresponding to a temperature of 470480 F. for a period of 40 minutes, with a resulting recovery of 79% of the potassium present in the greensand.

It has been shown in prior patents (U. S. Patent 1,329,369, Charlton, 1920, and 1,334,- 989 Charlton 1920), that potassium hydrate may be recovered from greensand by digesting with lime alone. It is also known that the presence of caustic alkali in addition to the lime is beneficial in the recovery of potassium hydrate from many of the naturally occurring potash carrying materials. (C. S. Patent 1,346,002, Charlton, 1920.) We are also aware that potassium nitrate may be obtained from greensand when the latter is digested with l me and sodium nitrate. (U. S. patent application, Serial Number, 401,498, Charlton, 1920.) In the present invention we have advanced a step further and have discovered that the Application filed August 29, 1920. Serial No. 406,673.

presp nce of caustic soda in addition to the sodiunrr nitrate and lime, is beneficial.

'llhelatter discovery is not only valuable in that it aflords'a method of recovering potassium but also because it permits the use of side products. That is the liquor resulting from the digestion of greensand,

. l'me and sodium nitrate'may be used either as it is formed or after a portion of the potassium nitrate is removed by concentrating and crystallizing out. In the latter case the percentage of caustic is very high.

In this as in all digestion methods of treatment of greensand, very fine grinding and continuous agitation are not only advisable but absolutely essential to procure a high yield.

While in this case we have specifically mentioned sodium nitrate as the salt to be added we do not wish to be limited to this. Speaking broadly, any alkali-metal salt capable of reacting with a solution of calcium hydroxide to form an alkali-metal hydroxide may be used.

To the digestion mixture is added a salt having an acid radicle that it is desired to combine with the potassium. To reen sand, lime and water may be added sodium nitrate to obtain potassium nitrate and caustic soda; sodium sulphite to obtain potassium sulphite and caustic soda; sodium nitrite to obtain potassium ntrite and caustic soda; sodium bromide to obtain potassium bromide and caustic soda; sodium chlorate to obtain potassium chlorate and caustic soda .sodium acetate to obtain potassium acetate and caustic soda; sodium borate to obtain potassium borate and caustic soda; sodium cyanide to obtain potassium cyanide and caustic soda; sodium ferrocyanide to obtain potassium ferrocyanide and caustic soda; sodium ferricyanide to obtain potassium ferricyanide and caustic soda; sodium fluoride to obtain potassium fluoride and caustic soda; sodium fluosilicate to obtain potassium fiuoslicate and caustic soda; sodium aluminate to obtain potassium aluminate' and caustic soda; sodium chromate to obtain potassium chromate and caustic soda; sodium citrate to obtain potassium citrate and caustic soda; sod'um hypochlorite to obtain potassium hypochlorite and caustic soda; sodium hypotsulphite to obtain potassium hyposulphite and caustic soda; sodium permanganate to obtain potassium permanganate and caustic soda; sodium perchlorate to obtain potassium perchlorate and caustic soda; sodium sulphide to obtain potassium sulphide and caustic soda; sodium tartrate to obtain potassium tartrate and caustic soda; etc. Of course some of the above do not lend themselves readily to methods of separation and are consequently of less value than the usual and beneficial method of concentrating and finally separating two valuable products. When the greensand is digested as in the example mentioned above, the resulting liquor is enriched in both potassium nitrate and caustic soda. If now the bulk of the potassium nitrate is removed and the remaining liquor employed in a digestion the strength of the caustic soda solution is materially increased.

The potassiumnitrate resulting from this process is of remarkable purity. In fact U. S. P. material may be obtained in one crystallization, the only impurity of any extent consisting of a slight amount of adhering caustic soda which may be removed by dampening with dilute nitric acid.

It will now be clear that by operating under these conditions we are enabled to obtain two valuable products with the minimum expense for evaporation and obtain maximum yields.

It is obvious that those skilled in the art may vary the details of the )rocess without departing from the spirit 0 the invention and therefore we do not desire to be limited to the above disclosures except as may be re uired by the claims.

e claim:

1. A process of producing a potassium salt which comprises digesting at elevated temperatures and under superatmospheric pressures greensand, line (CaO), an alkali-.

producing potassium ninitrate by crystallization; substantially as described.

4. A processof producing potassium nitrate which comprises digesting parts greensand, 85 parts of lime (CaO), 10.15 parts sodium nitrate, 14.3 parts sodium hydroxide, 36.15 parts potassium nitrate and 425 parts water under steam pressure at a temeprature of 470-480 F. for a period of 40 minutes; substantially as described.

THOMAS C. MEADO'WS. MATHIAS HAUBER, JR. HARRY WILLIAMS CHARLTON. 

